Does blood on an eggshell make the egg unfit for consumption?

Not on its own. Blood stuck to an unbroken shell takes the egg out of Class A, because that class requires a clean shell (RIISPOA, art. 225, I). The egg is unfit only if the shell is broken and dirty (art. 500, VI) or if the blood reaches the white (art. 500, I).

Can a camera detect blood spots inside an egg?

No. A surface camera sees only the shell. Blood spots inside show up on candling, which is mandatory in egg establishments (RIISPOA, art. 223, II). That is why the camera and candling complement each other.

What is the difference between blood on the shell and a blood spot in the egg?

Blood on the shell is material stuck to the outside, treated as dirt (7 CFR 57.1). A blood spot in the egg is inside, in the white or the yolk, and is an internal defect: a small, few spot is Class B (art. 226, II), and one that reaches the white makes the egg unfit (art. 500, I).

Explainer · Defects and grading

Is blood on an eggshell dirt or an internal defect?

Blood stuck to the shell is dirt: the egg falls out of Class A, which requires a clean shell (RIISPOA, art. 225). A blood spot inside the egg is an internal defect, and its destination depends on its size and whether it is in the white or the yolk. A camera sees only the shell, so candling is still needed for the inside of the egg.

Updated October 9, 2026 · 4 min read

Is blood on the shell dirt?

Yes. Blood stuck to an unbroken shell is foreign material on the outside, and the American definition of a dirty egg covers exactly that case: an unbroken shell with adhering dirt or foreign material (7 CFR 57.1).

In Brazil, Class A requires a clean shell (RIISPOA, art. 225, I). So an egg with blood on its shell does not qualify, even when the inside is perfect. Blood on the shell is treated as dirt, not as an internal defect.

How does a blood spot end up inside the egg?

Internal blood spots form inside the egg while it is being made, before the shell is complete. That is why they do not show on the shell: the blood stays in the white or the yolk. They are internal defects, and the method for detecting them is candling, not surface inspection.

Where does each case end up?

The destination depends on where the blood is and how much of it shows. The table summarises what RIISPOA says for each case.

Blood on the egg: legal classification and detection (the detection column is practical judgement)
Where the blood is	Classification	Basis	How it is detected
Outside, stuck to an unbroken shell	Dirty, outside Class A	RIISPOA, art. 225, I; 7 CFR 57.1	Visual inspection or camera
Inside, small and few in the white or yolk	Class B, for industrial processing	RIISPOA, art. 226, II and sole paragraph	Candling
Inside, reaching the white	Unfit for human consumption	RIISPOA, art. 500, I	Candling
Broken, dirty shell with blood	Unfit for human consumption	RIISPOA, art. 500, VI	Visual inspection or camera

In the detection column, candling covers what is inside the egg, and the camera reaches only what is on the shell.

What can a camera see of blood, and what can't it see?

A surface camera sees the shell: a red or brown stain stuck to it, with an irregular edge, is easy to notice. It cannot see the inside, so a blood spot inside the egg does not show up for it.

That is why a camera does not replace candling. RIISPOA requires examination by candling (art. 223, II), and the camera's role is to remove what is visibly dirty from the line before it. The full comparison is in candling or computer vision.

What should you do when blood appears on the shell?

The answer depends on where the blood is. These are the practical steps the line should have defined:

Separate eggs with blood stuck to the shell, so that they do not enter Class A.
Check whether the shell is broken: if it is broken and dirty, the egg is unfit (art. 500, VI).
Send eggs with an unbroken shell to candling, to check the inside.
Record the reason and the destination of each egg, so that the decision can be audited.

An egg with blood stuck to an unbroken shell and no internal defect does not meet Class A. If it is considered harmless, it falls into Class B, which is destined exclusively for industrial processing (RIISPOA, art. 226, I and sole paragraph).

Frequently asked questions

Does blood on an eggshell make the egg unfit for consumption?: Not on its own. Blood stuck to an unbroken shell takes the egg out of Class A, because that class requires a clean shell (RIISPOA, art. 225, I). The egg is unfit only if the shell is broken and dirty (art. 500, VI) or if the blood reaches the white (art. 500, I).
Can a camera detect blood spots inside an egg?: No. A surface camera sees only the shell. Blood spots inside show up on candling, which is mandatory in egg establishments (RIISPOA, art. 223, II). That is why the camera and candling complement each other.
What is the difference between blood on the shell and a blood spot in the egg?: Blood on the shell is material stuck to the outside, treated as dirt (7 CFR 57.1). A blood spot in the egg is inside, in the white or the yolk, and is an internal defect: a small, few spot is Class B (art. 226, II), and one that reaches the white makes the egg unfit (art. 500, I).

Sources

Decreto nº 9.013/2017 (RIISPOA), Presidência da República (Brasil)
7 CFR § 57.1 Definitions (Inspection of Eggs), U.S. Electronic Code of Federal Regulations

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